The present disclosure relates to a multilayer ceramic capacitor and a board having the same mounted thereon.
A multilayer ceramic capacitor, one of multilayer chip electronic components, is a chip-type condenser mounted on printed circuit boards of various electronic products such as display devices including liquid crystal displays (LCDs), plasma display panels (PDPs), and the like, computers, personal digital assistants (PDAs), and mobile phones to serve to charge or discharge electricity.
Since such a multilayer ceramic capacitor (MLCC) has advantages such as a small size, high capacitance, easiness of mounting, or the like, the multilayer ceramic capacitor may be used in various electronic devices.
The multilayer ceramic capacitor may have a structure in which a plurality of dielectric layers and internal electrodes having opposite polarities and interposed between the dielectric layers are alternately stacked.
Since the dielectric layers have piezoelectric and electrostrictive properties, when direct current (DC) or alternating current (AC) voltage is applied to the multilayer ceramic capacitor, a piezoelectric phenomenon occurs between the internal electrodes, causing vibrations.
Such vibrations may be transferred to a printed circuit board through external electrodes of the multilayer ceramic capacitor, such that the entire printed circuit board becomes a sound reflective surface to generate a vibration sound as noise.
The vibration sound may have a frequency corresponding to an audio frequency range of 20 Hz to 20000 Hz making listeners uncomfortable. The vibration sound, potentially providing unpleasant feeling to listeners, is known as acoustic noise.
In order to decrease the acoustic noise, research into a product having an increase in a thickness of a lower cover layer of the multilayer ceramic capacitor has been conducted.
In addition, when the multilayer ceramic capacitor having a relatively thick lower cover layer is mounted on a printed circuit board, such a thick lower cover layer may be positioned downwards in order to decrease the acoustic noise, resulting in a horizontal mounting type multilayer ceramic capacitor.
However, in the case in which the product having the multilayer ceramic capacitor with the thick lower cover layer is mounted on a board, it may topple over and mounting defects may frequently occur.
Meanwhile, chipping defects, resulting from ceramic bodies being crashed into each other and being broken, may occur in a process of manufacturing multilayer ceramic electronic components. In order to prevent the chipping defects, a method of polishing edges and corners of the ceramic bodies has been used.
However, in the case in which the polishing process is excessively or insufficiently performed on the edges and the corners of the ceramic body, this may affect reliability of the multilayer ceramic electronic component.
Therefore, research into a multilayer ceramic electronic component having improved reliability by decreasing acoustic noise and preventing mounting defects (that is, blocking the multilayer ceramic electronic component from toppling over when mounted on a board) and chipping defects has been still demanded.